The present invention provides a densifying agent adopted a total weight of a refined pitch which is 100 as a basis, the composition of the refined pitch includes 19-30 toluene insolubles (TI) by weight, 0.1˜0.3 quinoline insolubles (QI) by weight, 0˜0.001 ash by weight and 18˜30 quinoline solubles (QS) by weight, in which the temperature of the softening point of the refined pitch is in the range of about 120° C. to 140° C. Accordingly, the amount of the toluene insolubles (TI) and the small amount of the quinoline insolubles (QI) can be mixed with the carbon-based material to increase the density of the carbon-based material, and the content of the quinoline solubles (QS) is used for adjusting the binding effect of the densifying agent with the binder.